ABSTRACT Advance care planning (ACP), including end-of-life (EOL) discussions and decision-making, are important elements for the care of chronically and critically ill patients. Ideally, doctors would have conversations with patients with incurable, life-limiting illnesses about treatment options, based on the patient?s goals and values. These conversations cover how aggressively to treat an illness as well as the option eventually for hospice. These conversations ideally should happen long before a patient dies or becomes too ill to have these discussions. However, in many cases, ACP discussions between patients and providers do not occur. In response to this need for ACP, including EOL discussions and decision-making, some important changes have occurred. Nationally, a framework for standardizing patient preference forms ? Physician Orders for Life Sustaining Treatment (POLST) or their equivalent ? have been developed and introduced on a state-by-state basis. California adopted POLST in 2009 and began routinely collecting POLST as a supplement (Section S) to the Long-Term Care Minimum Data Set (MDS) for nursing home residents. Nationally, CMS began in January 2016 to reimburse providers to have ACP discussions, creating an incentive for providers to initiate, revisit, and report these discussions. The combination of these two separate policy interventions ? state-by-state implementation of POLST and Medicare reimbursement for ACP discussions ? allow for empiric evaluation of patient preferences and their impact (when collection is encouraged/facilitated) on care choices and outcomes. Using national nursing home data (MDS), California MDS Section S, Medicare enrollment data and FFS claims, and California all-payer hospital data (years 2011 to 2018), we propose the following aims and associated hypotheses for the evaluation of the impact of standardization and financial incentives related to ACP discussions in Medicare enrollees 65 years of age and older: 1. Assess the impact of POLST rollout on utilization of care at EOL and quality of care at the EOL among FFS Medicare patients in nursing homes nationally. 2. Assess the impact of Medicare FFS payment policy for ACP discussions on utilization of care at EOL and quality of care at the EOL among FFS Medicare patients in nursing homes nationally. 3. Assess the impact of Medicare payment policy for ACP discussions on POLST completion, patient preferences, and utilization of care at EOL and quality of care at the EOL in California nursing home residents enrolled in Medicare. This study will evaluate the policy impact on care for the elderly nationally and will leverage unique routinely collected POLST data from California to quantify the direct impact of physician incentives on patient preferences. Study results will be a catalyst for further innovation in ACP discussions and EOL planning.